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I would like to control a remote 12-24V To 5V 3A Step Down Power Supply via it's Enable pin, using the Witty Pi 4 Mini Cathode/VOUT supply. The supply source is from the same battery that supplies the Witty.
This pin needs to be pulled low to turn off the power supply. Alternatively I think I can remove the built in pullup resistor and externally pull the pin high (with a pulldown resistor to turn it off).
My problem lies with the fact that the manual says the GROUND pins on the Witty are NOT the ground for the Pi. So I'm unsure how I can use the reference voltage at VOUT to control a device that is connected to GROUND, not CATHODE.
Can I safely reference VOUT to GROUND? ie can I feed VOUT to the power supply enable pin which uses the common battery ground (via a suitable resistor)?
Posted : 10/05/2024 12:08 am
There is only a 0.05R resistor between CATHODE and GROUND, and it is for measuring the output current.
Even if the output current goes to 3A, the voltage drop on this resistor is just 0.15V. It is safe to reference VOUT to GROUND in your use case.
Posted : 10/05/2024 8:07 am